Extracts of the bovine tracheal mucosa have an abundant peptide with potent antimicrobial activity. The 38-amino acid peptide, which we have named tracheal antimicrobial peptide (TAP), was isolated by a sequential use of size-exclusion, ion-exchange, and reverse-phase chromatographic fractionations using antimicrobial activity as a functional assay. The yield was -2 ,ug/g of wet mucosa. The complete peptide sequence was determined by a combination of peptide and cDNA analysis. The amino acid sequence of TAP is

In an effort to clarify the role of amino acid hydrophobicity at the beta 6 position in sickling we have made recombinant hemoglobin tetramers containing beta 6 Val (Hb S) and beta 6 Leu (Hb Leu). Recombinant Hb S and Hb Leu had the same electrophoretic mobility, chromatographic behavior, and absorption spectrum. The deoxy form of both tetramers polymerized in high phosphate buffer (1.8 M) and exhibited distinct delay times prior to polymerization. The kinetics of polymerization for recombinant and native Hb S were similar, while recombinant Hb Leu polymerized more readily. The solubility of deoxy Hb Leu was less than deoxy Hb S, indicating that rapid polymerization and decreased solubility of deoxyhemoglobin is accelerated with increasing hydrophobicity at the beta 6 position.

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